Analog to digital converters convert continuously varying analog signals into digital signals, such as binary code readable by processors, computers and other digital devices and systems. Analog to digital (A/D) conversion is useful for allowing the many kinds of continuously variable analog signals that characterize diverse real world phenomena, such as alternating current electricity, temperature, pressure, light and other radiation, sound, movement, and a wide variety of many others, to be converted into a form that can be read and processed by computers. This allows computerized monitoring, control, and other functions in response to the analog signals.
A modern analog to digital converter (ADC) may be deployed on an integrated circuit (IC). A single IC may deploy a single or multiple ADC circuits, and thus constitute a dedicated ADC device. With the miniaturization and functional capability inherent in some modern ICs, an ADC may constitute one circuit deployed thereon. One such modern IC is the microcontroller, which effectively constitutes a computer functionality on a single IC. Microcontrollers incorporate a processor, a clock, read only and random access memories, and an input/output (I/O) unit, integrated into a single chip. Some microcontrollers are user programmable.
Fixed counters characterize typical conventional ADCs. For some conventional ADCs, their full scale is fixed as well, and thus not adjustable. For other conventional ADCs, the full scale is adjustable. Typically however, for conventional ADCs that allow it, the full scale adjustment is adjustable in fixed powers of two, or as multiples of a minor conversion factor. Some conventional ADCs can be adjusted by varying a reference voltage thereto, which can for instance change the gain of the ADC allowing a known result for a given input voltage being converted. But whether a conventional ADC is adjustable or not, once set, its full scale count is not typically changeable.
Conventionally, ADCs are calibrated in one of two ways. Some conventional ADCs are calibrated by adjusting a reference voltage, which can for instance change the gain of the ADC, so as to achieve a specifically desired ADC result. On other conventional ADCs, the reference voltage remains fixed and a scaling factor is selected and applied to calculating the conversion result. Such scaling factors are typically a fixed or a floating point value by which an actual conversion result is multiplied or divided to achieve a scaled result. The scaling factor is scaled into each and every ADC result after the conversion.
Fixed scale conventional ADCs can be less convenient for some applications than adjustable scale conventional ADCs. Adjustable conventional ADCs must be manually calibrated, such as wherein the reference voltage is changed by manipulating a mechanically adjustable potentiometer. Further, the fixed powers of two based conversion result outputs characterizing some adjustable conventional ADCs can be inconvenient mathematically. Conversion result outputs characterizing other adjustable conventional ADCs that use multiples of fixed scaling factors can also be mathematically inconvenient. For instance, to handle the conversion result outputs of adjustable conventional ADCs, IC operations such as processing, memory usage, and the like, typically engage in fixed and/or floating point arithmetic.
Manual calibration (e.g., adjustment of the reference voltage with a potentiometer or similar mechanically or otherwise actuated electrical device) can be time consuming, labor intensive, error prone, and inefficient. The mathematically inconvenient conversion result of adjustable conventional ADCs can demand handling using fixed and/or floating point arithmetic. Fixed and floating point arithmetic operations typically make demands on processing and memory resources. Such demands can increase the time needed to calculate conversion results, which can increase the time needed to perform a conversion and reduce the sampling availability of the ADC. Such inefficiencies may thus characterize conventional ADCs, even those deployed on single ICs such as microcontrollers.